The invention relates to automatic selection of microphone signals.
Noise and reverberance have been persistent problems since the earliest days of sound recording. Noise and reverberance are particularly pernicious in teleconferencing systems, where several people are seated around a table, typically in an acoustically live room, each shuffling papers.
Prior methods of reducing noise and reverberance have relied on directional microphones, which are most responsive to acoustic sources on the axis of the microphone, and less responsive as the angle between the axis and the source increases. The teleconferencing room can be equipped with multiple directional microphones: either a microphone for each participant, or a microphone for each zone of the room. An automatic microphone gating circuit will turn on one microphone at a time, to pick up only the person currently speaking. The other microphones are turned off (or significantly reduced in sensitivity), thereby excluding the noise and reverberance signals being received at the other microphones. The gating is accomplished in complex analog circuitry.